ΔE 14.3, fair: the same colour family, but not a straight swap. Plate Armour is noticeably darker than Polished Silver.
Can I use Plate Armour instead of Polished Silver?
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Plate Armour is noticeably darker than Polished Silver.
Can I use Polished Silver instead of Plate Armour?
The same difference applies the other way round: Polished Silver is noticeably lighter.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.